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Front Microbiol. 2015 Jun 30;6:646. doi: 10.3389/fmicb.2015.00646. eCollection 2015.

Marked increase in incidence for bloodstream infections due to Escherichia coli, a side effect of previous antibiotic therapy in the elderly.

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Service de Bactériologie et Hygiène, Centre Hospitalier Universitaire de Tours, UMR 1282 Tours, France ; Réseau des Hygiénistes du Centre, Centre Hospitalier Universitaire de Tours France.
Service of Hospital Preventive Medicine, Lausanne University Hospital Lausanne, Switzerland.
Service d'Hygiéne Hospitaliére, Centre Hospitalier Universitaire de Besançon, UMR CNRS 6249, Chrono-environnement, Université Bourgogne Framche-Comté Besançon, France.
Service de Bactériologie et Hygiène, Centre Hospitalier Universitaire de Tours, UMR 1282 Tours, France.


We conducted a survey including 3334 bloodstream infections (BSIs) due to E. coli diagnosed in 2005-2014 at a stable cohort of hospitals. Marked increases in incidence were observed for community-acquired (CA) BSIs in patients aged >75 years, CA-BSIs of digestive origin in patients aged 60-74 years, healthcare-associated BSIs, and BSIs associated with ESBL (extended-spectrum B-lactamase)-producing E. coli (ESBLEc). Using MLST, we studied the genetic diversity of 412 BSI isolates recovered during the 2014 survey: 7 major sequence type complexes (STCs) were revealed in phylogenetic group B2, 3 in group A/B1 and 2 in group D. Among the 31 ESBLEc isolates, 1/3 belonged to STC 131. We searched for possible associations between clonal groups, clinical determinants and characteristics of BSIs: isolates from groups B2 (except STC 131) and D were susceptible to antibiotics and associated with BSIs of urinary origin in patients <60 years. STC 131 and group A/B1 isolates were multi-drug resistant and associated with CA-BSIs of digestive origin in patients aged 60-74 with a recent history of antibiotic treatment. STC 131 isolates were associated with HCA-BSIs in patients with recent/present hospitalization in a long-stay unit. We provide a unique population-based picture of the epidemiology of E. coli BSI. The aging nature of the population led to an increase in the number of cases caused by the B2 and D isolates generally implicated in BSIs. In addition, the association of a trend toward increasing rates of gut colonization with multi drug-resistant isolates revealed by the rise in the incidence of BSIs of digestive origin caused by STC 131 and A/B1 (STCs 10, 23, and 155) isolates, and a significant increase in the frequency of BSIs in elderly patients with recent antibiotic treatment suggested that antibiotic use may have contributed to the growing incidence of BSI.


Escherichia coli; ST 131; antibiotic; bloodstream infection; elderly

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